Suspension device for electric traction motors



C. R. DEMOLE.

SUSPENSION DEVICE FOR ELECTRIC TRACTION MOTORS.

APPLICATION FILED MAY 23. 1922.

1 $25,454. nted Aug 8, 1922.

2 SHEETS-SHEET I.

Zrlra 71 Tan:

C- R. DEMOLE.

SUSPENSION gEvlcE FOR ELECTRIC TRACHON MOTORS.

APPLICATION FI'ED MAY 23 1922 Patented Aug. 8, 1922,

50 57 54 5 f I f fizz! #-%fl %ha SUSPENSION DEVICE FOR ELECTRIC TRACTIONllIOTORS.

Application filed May 28,

To aZZ 207mm it may concern:

Be it known that I, CrL-inrins ltoonn Dn- MOLE, engineer, a citizen ofSwitzerland, re siding; Geneva, Canton of Geneva, in the Confederationof Switzerland, have invented certain new and useful ImPIOYGiHGHlJS inSuspension Devices for Electric Traction Motors, of which the followingis a specification.

The object of this invention is an improved device for suspending motorsused in electrically propelled vehicles.

The electric traction motors working on an axle by means of a suitablegearing are usually fixed on the one part onto either the said axle or ahollow shait surrounding the same without the intermediary of anyelastic member by means of lugs provided with bearings for receiving theaxle or the shaft, and on the other part onto the truck or the bogie ofthe vehicle by means of elastic sus pension members such as springs. inthis way about half of the motor weight is sup-- ported directly by thebushes ot' the axle or the hollow shatt. The wear of these bushes is dueto a considerable extent to the sum oi the following two efi'ects:

1st: The friction resulting from the weight of the axle or the shaftsupported by the bushes;

2nd: The often rather heavy blows which result owing to this weight whenthe vehicle is rolling over rail joints or other unevenncsses oi thetracl: or road.

According to the invention this wear is avoided due to the fact that thesusoens. on device comprises an intermediate frame resting by means ofsprings upon the axle box s and supporting the motor, said springs beingadjusted in such a manner that their tension counterbalances the forceacting on the bushes by which the mot-or is connected to the shaft whichit rotates, one which force is caused by the weight of the motor, thedescribed arrangementserving to reduce the wear of said bushes and torender the suspension independent from the frame of the vehicle. whilstallowing to suspend the total weight of the motor on sorings.

The attached. drawing illustrates by way of example anddiagrannnatically two workinp; forms of the invention. Fig and. 2 anelevational and plan view, re pectively,

Specification of Letters Patent.

Patented Aug, 8, 1922.

1922. Serial No. 563,115.

of a first working form adapted for the suspension of a single motor andFigs. 8 and i show equally in elevation and in plan asecond working formfor suspending a twin motor.

Figs. 5 and 6 are an elevation and plan view, respectively, showing theapplication. of an anchoring device to the twin motor construction shownin Figs. 3 and 4.

According to Figs. 1 and 2 the single traction motor a of the usualoctagonal shape is working directly upon the axle a by a pinion c and bya toothed wheel cZ fixed rigidly upon the axle. On the one side of theaxle Z) the motor is provided with two long and parallel shanks a acarrying; the axle bearings. On the opposite side ot said axle the motoris provided with lugs a The extremities of the shanks a a and the lugs ahave holes for the passage of ve tical rods f, g, 72 and 2' upon whichare positioned the coiled springs j, 76, Z, m. The springs 7 and Z hearat one extremity against the rectangular intermediate frame a arrangedabove the axle Z) and the springs 70 and 771 bear at one entremityagains; washers g and 2' held on the rods by screw nuts and 5 T he frameit rests on the axle journal boxes 6 by means of supports a links 0, andleaf springs 0 whose flexibility is due rather to their length than tothe cross section whica they are given.

The motor a is on its top surface provided with two projections a whoseaxes are in the vertical plane through the center of gravity of the massconstituted by the motor and the intermediate frame. These projectionsare adapted to serve supports for an anchoring device similar to thatshown in Fins. 5 and 6.

The described form of the suspension device according to Figs. 1 and 2operates as follows:

Owing to the screw nuts 9 2' which may be displaced on the rather long,threaded portion of the rods 7, 9, 7t and "Z, it is possible to vary thetension or stress of the springs j, Z3, Z, on within large limits, whichstress is taken up by the said screw nuts and the laminated springs p.

The tension of ranged in pairs on each one of the rods f, 9, 7L. and imay be adjusted in such a manner. that the portion of the weight whichin the the springs y, 3, Z, m are known suspension devices would have tobe supported by the axle bushes is taken up by atorce acting in theinverse or upward direction. l1? said force connteu balances thisrespective portion oi? the motor weight, the pressure of the axlebearing on the axles becomes Zero as well as the friction due to suchpressure. The shocks or blows caused by the unevenness of the track orroad are, however, transn'iittcd to the bearings. It the active force isdouble that of the weight of the particular portion of the motor whichin other motor suspensions would hear on the axle bushes, a pressurewill result on th axle bearings which is equal to the said weight, butwhich is dirccted upwardly.

In this second case the wear of the bushes due to the friction resultingfrom this pressure will be equal to that mentioned above but the wearinstead of afi'ecting the top part of the bushes, will ailect theirlower part. The unevennesses of the track or road do however not giverise to shocks or blows oi. the motor and of the axle bushes on theaxle. They will on the contrary cause a transitory reduction of theupwardly directed pressure at the axle bushes on the axle. It is to benoted that except in some rare cases, these shocks or blows will by nomeans be able to cause a momentary reduction down to zero of thepressure of the motor underneath the axle since the energy which theyrepresent is immediately taken up by the springs. For this reason it isnot necessary to stress the springs to such a degree as has been necessary in the second case. The wear of the inner part of the axle bushesmay therefore be brought down to a value which very much smaller thanthat which would correspend to the wear of the upper part of the axlebushes oi? a motor suspended in the usual way. Nevertheless a greatmajority of the blows will not be transmitted to the axle bushes andthose which are so violent that they are not entirely taken up by thesprings will at any rate be considerably damped or absorljied. i

From the above itbecomes evident that the wear oi the axle bushes willbe no longer due to the sum oi? the two causes mentioned in the firstpart of this specification, but will. be equal to their difference,which by means oi. suitable adjusting might theoretically be broughtdown to a value near zero. This latter value is dependent first of allupon the speed of the vehicle and the state of the tracker road, whichtwo factors determine the violence of the blows orshocl-zs. The tensionof the springs should therefore be adjusted before taking up the serviceon a given line or route in accordance with that required tor the firstvehicle of each particular type. it is preferable to choose the tensiondefinitely a little higher than woul d cor- .carr T unions 5 5 which intwo oo'or.

respond to the value determined by the trials, for the simple reasonthat whilst the friction in the bushes only causes a wear in them, thesudden and violent blows have the great inconvenience that the electricin sulations inside the motor are often damaged and certain parts of themotor get out of order.

Owing to the new suspension. device, the whole motor weight is suspendedon springs and the axle is the only part of the vehicle which is notyieldingly suspended. The whole of this welght is besides transmitted tothe axle boxes which ma stand a much greater wear than the axle busheswithout requ'. 'ing a revision and which are lllllCll'lTlOlG easilyaccessible than the axle bearings.

Since the motor is suspended on the one part independently from theframe of the truck or from the vehicle bogie, and on the other part fromthe box of the vehicle, the vibrations which may occur are localized andwill be transmitted neither to this trucl; or bogie nor to the vehiclebox. Hence the noisecauscd by such vibrations owin to the resonai'ice otthe box will. largely be reduced.

The twin motor as shown in Figs. 8 and i coi'uprises two like parts 1, 2symmetricall arranged on both sides ot the axle, and which are united byribs 3 cast in one piece with the casings; the arinatures oi the motorsare keyed. on to shalts 1 ,4 The latter a he points engage with a wheel(Z which is common to both and is keyed onto the axle l). Thegeometrical axes oi"? the shalts l", 43* and. of the axle 7; arenormally in the same horizontal plane. The axle bushes of the motor arerigidly iixed onto theribs 3.

The intermediate iirame 6 consists, in this working form, of twohorizontal rectangular itranties 6 6' arranged, respectively, above andbelow the axle l), and connectedat their corners by the uprights 6 Theintermediate frame 6 is connected. by the supports (3, (3

to the axle b xcs con. both sides oil? which are arranged. thesyniings9, 10 of: each pair. Between the rcctan nilar frames 6-, (3 are anranged the coiled springs j, Z1, 1, and m are arranged acting by pairson the lugs 11 1]. which are provided on each side of. the motor 1-2.The tension or these springs may be adjusted, the same in the case ofthe first working form, by means of washers i and screw nuts 9 which therods j", g, h, i, are fitted with. i

The sus )ension springs may of course be arranged. also in anotherteacher than the one shown in 3 andsi.

Since the two pinions 5 5 of thistwin motor engage the wheel a? in aninverse ditownie will. be produced whose axis of the verticalrods 72.,'2', onto which all) rotation is the axis of the axle Z; and which doesnot give rise to a reaction on the axle bushes. Hence a good deal of theplay is avoided which is caused by the wear of these axle bushes. it isnow alloi'wablo to provide for a slight vertical play of the whee (Zbetween the pinions 5 and instead of fixing the axle bushes rigidly onthe ribs 3 to give them a very slight play in vertical slides arrangedbelow these ribs, whilst otherwise the engagement of the teeth ismaintained even more precise than in the case of the play which one hadto take account of up to now for the reason of the usual wear of theaxle bushes. Between the ribs and the axle bushes springs are inserted.The vertical play provided for never intervenes except in the case ofexceptional blows and only for very short intervals. It willnevertheless function to stress the springs 7', 7c, Z and m less and toreduce even more the slight wear which said tension or stress mightotherwise produce. It comes in fact to this that the function of theaxle bushes becomes that of mere guiding members.

The entire weight of the twin motor rests by the intermediary of springson the axle boxes in such a manner that the anchoring device, which willnow be described, will transmit horizontal strains only.

Referring to Figs. 5 and 6, pair of spaced vertical lugs 29 are fixed attheir lower ends to the casing of the motors l and 2 between theconnecting ribs 3. A rod 30 is journalled at one end between the upperportions of said plates upon a pin and at its other end is formed with ahead 85. A

econd rod 31 is journalled at one end to t is vehicle frame 1* upon apin 3% and at its other end is formed with a head 36. The rods 30 and 31are arranged in overlapping relation between the heads and the rod 30passing through the perforation in the head 36 and the rod 31 passingthrough a perforation in the head 35. A coil spring surrounds the rods30 and 31 between the heads 35 and 86 and is fixed at its ends to saidheads. The parts 29 to 36, inclusive, form a yielding anchoring devicebetween the motors 1 and 2 and the vehicle frame 9* which transmits onlyhorizontal stresses. As already stated, similar anchoring devices may beprovided between the motor a of Figs. 1 and 2 and the frame 7 It is tobe understood that the anchoring device may be of any other suitableconstruction. than the one shown by way of example in Figs. 5 and 6.

An important advantage of the second working form resides in the factthat the center of gravity of the mass comprising the twin motor and theintermediate frame is essentially in the axis of the axle 7). For thisreason the moment of the mass on this axis is practically zero. Owing tothe fact, that .the force caused by the swings is not sut to or is notsuddenly subtracted from this I the tractive effort, which would cause ajerking run and often even longitudinal trepidatrons of the vehicle. Infactthe suppression of the sudden variations of the effort trans mi tedto the axle essentially improves also the working conditions for thearmatures and the gearings.

The twin motor may advantageously be made use of for locomotives butowing to its low and elongated form in the direction of the length ofthe vehicle it may be particularly adapted for automobile railway carsand for tramways.

In both the working forms shown, the motor drives the axle directly bymeans of an intermediary gear. It could also be provided that the driveis not direct but is ob tained by a hollow shaft which by means of agear is rotated, said hollow shaft surrounding the axle. In this casethe intermediate frame would bear on the axle boxes and the springswould be adjusted in such a way that their tension would counterbalancemotor weight and acting on the bearings by which the motor connectedwith the hollow shaft. The use of such a hollow shaft which allows a certain displacement of the axle with regard to the motor, may be ofadvantage. The displacement of axle within the shaft is re duced to aminimum since it does correspond solely to the displacement of the motorand no longer to the sum of the several displacements of the wholevehicle with regard to the axle.

The suspension device might in the case of a single motor (Figs. 1 and2) also comprise an intermediate frame with two superposed frames, thesame as it might be made of a. single frame in the case of the twinmotor (Figs. 3 and 4).

The springs inserted between the intermediate frame and the motor mightalso be omitted.

Having now particularly described and ascertained the nature of myinvention and the manner in which it is to be performed, I declare thatwhat I claim is 1. A suspension device for electric traction motorscomprising in combination an intermediate frame bearing on the axleboxes by means of springs and supporting the motor, the connecting meansbetween the motor and its supporting frame comprising springs whichadjustable in such a manner that their tension is adaptedtocounterbalance the force acting on the bearings by which the motor isconnected to the shaft which it drives, and which. force is due to theweight and torque of the motor, whereby tb diminish the wear of. thebushes of said bearings, 2. ii. suspension device for twin electrictraction motors comprising in combination an intermediate frame bearingon the axle bones and supporting the motors, the connecting meansbetween the motors and their supporting frame comprising springs whichare adjustable in such a manner that their tension is adaptedtocounterbalance the force acting on the bearings by which the motors areconnected to the shaft wnich they drire, and which force is due to theweightand torque of the twin motors whose two armatures engage innormally are diametrically opposite one to another, by means of pinionswith. a common toothed whee]. fixed rigidly to the axle.

3h suspension device for electric traction motors comprising incombination an intermediate frame bearing on the axle boxes andsupporting the motor the connecting means between the motor and itssupporting :trame comprising springs which are adjustable in suchamanner that their tension is adapted to counterhal-(mce the forceacting on motor is connected to the shaft which. it drives, and whichforce is due to the weight and torque of the motor and an anchoringdevice adapted to connect the motor to the vehicle chassis in such amanner that only horizontal strains are transmitted.

'stantially in the two points, which by which springs which support thethe bearings by which the 4:. A; suspension device "for electrictraction twin motors comprising in combination an intermediate framebearing on the axle boxes and supporting the motors, the connectingmeans between the motors and their FHIPPOTlLlHg frame comprising springswhich. are adjustable in such. a nanner that their tension adapted tocounterbalance the force acting on the liiearings by which the motorsare connected to the shaft which hey drive, and which force is due tothe weight and torque oi the twin motors, the center of gravity of themass of the motors and intermediate frame being arranged subaxis oi":the axle, so that the weight moment of said mass with regard to the axleis practically zero.

5. A suspension device for tionmotors comprising in combination anintermediate frame bearing on the axle bones by means of springs andsupporting the motor, the connecting means between the motor and itssupporting frame comprising springs which are adjustable in such amanner that their tension is adapted to counterbalance the force actingon the bearings the motor is connected to the shaft which it drives. andwhich force is due to the weight and torque of: the motor the springs bywhich the intermediate :lramc is made to bear on the axle boxes and thetractive eitort of the motor being made to wort: independently from. oneanother. a

In. testimony whereof I have attired my signature in presence of twowitnesses.

CHARLES ROGER DEMOLE.

Witnesses Dr. Ron. on Wnonrnmnnnc, Eon. EUNNaNNn.

electric. trac-

